53a Branch of science concerned with the effects of extremely low temperatures on living organisms (11) I have C?Y?T?O?A?Y. I think the answer may be CRYOTHERAPY but that doesn't marry with 46d Freshwater salmonoid whitefish found in the Great Lakes. The only answer I can come up with is CISCO (the O clashes with the E in cryotherapy). Hope that all makes sense. Please help!